What is the greatest common factor of $25$ and $30$ ? Another way to say this is: $\operatorname{gcf}(25, 30) = {?}$
Answer: The greatest common factor is the largest number that is a factor of both $25$ and $30$ The factors of $25$ are $1$ $5$ , and $25$ The factors of $30$ are $1$ $2$ $3$ $5$ $6$ $10$ $15$ , and $30$ Thus, the greatest common factor of $25$ and $30$ is $5$. $\operatorname{gcf}(25, 30) = 5$